HOLY THURSDAY is the most complex and profound of all religious observances, except perhaps the EASTER VIGIL.
It celebrates both the institution by Christ himself of the Eucharist, the Priesthood, and His last meal with His disciples, a celebration of Passover, He the self-offered Passover Victim, that every ordained priest repeats at every mass they say, by His authority and command.
On Holy Thursday there is also a special Mass in the Cathedrals of the world, attended by as many priests of the diocese as can attend. The priests renew their ordination commitments and the holy oils are blessed and consecrated, it is called, The Chrism Mass.
It takes its name from the most used of the three holy oils in the church which the Bishop of the Diocese commissions for the local church's use during the following year. They are, the Oil of the Sick, used for the anointing of the sick, and the Oil of the Catechumens, which is imposed on those preparing for baptism (babies included), they are simply "blessed".
The third oil “The Oil of Chrism” is used at the ordination of priests and bishops, baptisms, confirmations, the consecration of altars and the blessing of churches, where the walls are smeared with it in the shape of the cross. This oil is "consecrated" and all the priests present participate in the consecration by extending their hands toward the vessel containing it as the bishop says the prayer of consecration. It includes balsam which is poured into the oil, it gives it a sweet smell intended to remind those who are consecrated with it the "odor of sanctity".
The Chrism Mass also provides an opportunity for the faithful of the diocese to show support for their priests.
On this day celebration of private Mass is forbidden. The evening Mass of the Lord's Supper, inaugurates the period of three days, known as the Easter Triduum, Good Friday, Holy Saturday and Easter Sunday.